But union machinists and painters voted no on Saturday. They wanted a $1.95 increase on an average $23.33-an-hour wage.

On Monday, workers went on strike, idling the Swan Island plant in North Portland that employs 725 union members and makes as many as 30 Western Star trucks a day.

The vote speaks to confidence among workers in a slowly recovering economy and a willingness to push back when companies try to set terms. Employees at the former Freightliner factory spurned the offer even though Daimler laid off about 250 earlier this year and almost closed the plant as recently as 2009.

"Employers will take advantage of the times and the fact that there are a lot of people unemployed," said Joe Kear, business representative and organizer at the International Association of Machinists and Aerospace Workers District Lodge W24 in Gladstone. "But the machinists and painters membership didn't think it was enough and rejected it."

The Machinists' union has been particularly active in Oregon, recently trying to organize Portland-area employees of Precision Castparts Corp. and launching a similar bid at Jeld-Wen Inc., based in Klamath Falls. Union leaders say the high-profile drives in one state are coincidental, but acknowledge they're constantly scouting opportunities.

At Precision, a big aerospace parts manufacturer whose workers rejected unionization last month, the main issue was not wages but working conditions, including forced overtime. At Jeld-Wen, a window-and-door maker, union organizers cite both wages and conditions they claim are abusive.

During three weeks of talks, the union team at Daimler objected to mandatory overtime, Kear said. The team also resisted the company's attempt to dilute benefits, he said, and to deny medical coverage in retirement for 111 eligible employees.

But the main issue remains wages, he said, as the union seeks a 65-cent-an-hour increase in each of three years. Pay has been frozen for four years at the plant, which operates one production shift a day, according to the union. Since 2010, Kear said, productivity has increased 25 percent, calculated by the ratio between workers and the increased number of trucks made.

A Daimler Trucks North America spokesman declined to confirm figures or to discuss the standoff. Dave Giroux, the company's public relations director, said in an e-mailed statement that the unions "did not unanimously ratify the contract offer" extended Friday. He said the company considers talks confidential.

Daimler workers began picketing at 12:01 a.m. Monday at the Swan Island plant, where the most recent strike, in 2007, lasted a week. The strikers are members of Machinists Local 1005 and the International Union of Painters and Allied Trades Local 1094. Other union members at the factory are represented by the Teamsters and the Service Employees International Union.

Targeting Jeld-Wen

At Jeld-Wen, the Machinists began trying to organize the manufacturing workforce in February. A unionization election could be a ways off, given the organization's rule of thumb requiring a 65 percent showing of interest among workers, said Bill Street, Portland-based director of the Machinists' woodworking department.

"We broke that rule at Precision Castparts and the result was what you might expect when you break a rule that exists for a really good reason," Street said. Precision workers voted 1,258 to 932 not to join the union in Oregon's biggest such private-sector election in more than 30 years.

Machinists organizers aim to unionize Jeld-Wen's North American workforce of about 5,500, partly on the basis of pay. "Probably a quarter of their workforce nationwide is eligible for food stamps, for SNAP, and that we think that's an issue," Street said.

Injuries are common at some Jeld-Wen plants, Street said, and workers say some supervisors are abusive.

A Jeld-Wen spokeswoman could not be reached Monday to respond to the accusations.